title: Disentangling the contributions of ontogeny and water stress to photosynthetic limitations in almond trees.
abstract: Very few studies have attempted to disentangle the respective role of ontogeny and water stress on leaf photosynthetic attributes. The relative significance of both effects on photosynthetic attributes has been investigated in leaves of field-grown almond trees [Prunus dulcis (Mill.) D. A. Webb] during four growth cycles. Leaf ontogeny resulted in enhanced leaf dry weight per unit area (W(a)), greater leaf dry-to-fresh weight ratio and lower N content per unit of leaf dry weight (N(w)). Concomitantly, area-based maximum carboxylation rate (V(cmax)), maximum electron transport rate (J(max)), mesophyll conductance to CO₂ diffusion (gm)' and light-saturated net photosynthesis (A(max)) declined in both well-watered and water-stressed almond leaves. Although g(m) and stomatal conductance (g(s)) seemed to be co-ordinated, a much stronger coordination in response to ontogeny and prolonged water stress was observed between g(m) and the leaf photosynthetic capacity. Under unrestricted water supply, the leaf age-related decline of A(max) was equally driven by diffusional and biochemical limitations. Under restricted soil water availability, A(max) was mainly limited by g(s) and, to a lesser extent, by photosynthetic capacity and g(m). When both ontogeny and water stress effects were combined, diffusional limitations was the main determinant of photosynthesis limitation, while stomatal and biochemical limitations contributed similarly.
authors.affiliation: Universidad Politécnica de Cartagena, Escuela Técnica Superior de Ingenieros Agrónomos, Área de Ingeniería Agroforestal, Paseo Alfonso XIII, 48, 30203, Cartagena, Spain,Soil Research Centre, Department of Geography and Environmental Science, The University of Reading, Reading, RG6 6DW, UK andInstituto de Recursos Naturales y Agrobiología, CSIC & Apartado 1052, 41080 Sevilla, Spain.
authors.forename: Gregorio
authors.initials: G
authors.lastname: Egea
authors.affiliation: Universidad Politécnica de Cartagena, Escuela Técnica Superior de Ingenieros Agrónomos, Área de Ingeniería Agroforestal, Paseo Alfonso XIII, 48, 30203, Cartagena, Spain,Soil Research Centre, Department of Geography and Environmental Science, The University of Reading, Reading, RG6 6DW, UK andInstituto de Recursos Naturales y Agrobiología, CSIC & Apartado 1052, 41080 Sevilla, Spain.
authors.forename: María M
authors.initials: MM
authors.lastname: González-Real
authors.affiliation: Universidad Politécnica de Cartagena, Escuela Técnica Superior de Ingenieros Agrónomos, Área de Ingeniería Agroforestal, Paseo Alfonso XIII, 48, 30203, Cartagena, Spain,Soil Research Centre, Department of Geography and Environmental Science, The University of Reading, Reading, RG6 6DW, UK andInstituto de Recursos Naturales y Agrobiología, CSIC & Apartado 1052, 41080 Sevilla, Spain.
authors.forename: Alain
authors.initials: A
authors.lastname: Baille
authors.affiliation: Universidad Politécnica de Cartagena, Escuela Técnica Superior de Ingenieros Agrónomos, Área de Ingeniería Agroforestal, Paseo Alfonso XIII, 48, 30203, Cartagena, Spain,Soil Research Centre, Department of Geography and Environmental Science, The University of Reading, Reading, RG6 6DW, UK andInstituto de Recursos Naturales y Agrobiología, CSIC & Apartado 1052, 41080 Sevilla, Spain.
authors.forename: Pedro A
authors.initials: PA
authors.lastname: Nortes
authors.affiliation: Universidad Politécnica de Cartagena, Escuela Técnica Superior de Ingenieros Agrónomos, Área de Ingeniería Agroforestal, Paseo Alfonso XIII, 48, 30203, Cartagena, Spain,Soil Research Centre, Department of Geography and Environmental Science, The University of Reading, Reading, RG6 6DW, UK andInstituto de Recursos Naturales y Agrobiología, CSIC & Apartado 1052, 41080 Sevilla, Spain.
authors.forename: Antonio
authors.initials: A
authors.lastname: Diaz-Espejo
mesh_terms: D057914:Agricultural Irrigation; D018533:Biomass; D002245:Carbon Dioxide / Q000378:metabolism; D003681:Dehydration; D004579:Electron Transport; D019277:Entropy; D058503:Mesophyll Cells / Q000378:metabolism; D008954:Models, Biological; D010788:Photosynthesis / Q000502:physiology*; D018547:Plant Stems / Q000502:physiology; D054046:Plant Stomata / Q000033:anatomy & histology / Q000502:physiology; D018526:Plant Transpiration / Q000502:physiology; D027861:Prunus / Q000254:growth & development* / Q000502:physiology*; D019655:Quantitative Trait, Heritable; D011891:Rain; D012621:Seasons; D013696:Temperature; D014867:Water
chemical_list: D014867:Water; D002245:Carbon Dioxide